If the error happens at one PC when the other PC is switched off then that sounds like a third device configured for fixed IP address at the start of the DHCP pool is coming online after the PC received its lease assignment. > I've not seen the problem with any other Netgear DG834G/GT/PN routers, and...

...routers seem to have poor connection issues from what I have read or seen by troubleshooting them, and until Netgear wakes up and issues firmware for all units to correct IP Address conflicts, they will continue to have connection issues, everything from wifi dropping to slow speeds and in short the fix...